Another injured victim, who suffered severe injuries in an attack allegedly by their tenant in Shibpur upazila on Sunday, succumbed to her injures at Dhaka Medical College Hospital (DMCH) yesterday, raising the death toll to four.
The deceased is Kulsum Begum, 23.
Earlier on Sunday, Kulsum's parents Tajul Islam and Monowara Begum of Kumradi village, and their tenant Badal Mia's wife Nazma Akter were killed by Badal in the same attack.
Inspector (Investigation) of Shibpur Police Station Abul Kalam said Badal, a carpenter from Kishoreganj's Pakundia upazila, had been living with his wife Nazma at a rented house owned by Tajul Islam since their marriage.
The couple often used to engage in altercation over various family issues.
On Sunday early morning, Hearing Nazma's screaming, house owner Tajul, his wife Monowara and daughter Kulsum rushed to the spot to rescue her.
Seeing them interfering, Badal started stabbing everyone present there indiscriminately with a knife leaving all the four critically injured.
Later, villagers took them to Narsingdi Sadar Hospital, where the doctors declared Najma and Monowara dead, while Tajul died on his way to DMCH.
Meanwhile, locals caught Badal and gave him a good beating before handing him over to the police.